CN113227672A - Refrigeration cycle device - Google Patents
Refrigeration cycle device Download PDFInfo
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- CN113227672A CN113227672A CN201980079923.1A CN201980079923A CN113227672A CN 113227672 A CN113227672 A CN 113227672A CN 201980079923 A CN201980079923 A CN 201980079923A CN 113227672 A CN113227672 A CN 113227672A
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- Prior art keywords
- refrigerant
- heat exchanger
- internal heat
- refrigeration cycle
- evaporator
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B40/00—Subcoolers, desuperheaters or superheaters
- F25B40/02—Subcoolers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B1/00—Compression machines, plants or systems with non-reversible cycle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B40/00—Subcoolers, desuperheaters or superheaters
- F25B40/06—Superheaters
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
- F28D7/10—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged one within the other, e.g. concentrically
- F28D7/106—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged one within the other, e.g. concentrically consisting of two coaxial conduits or modules of two coaxial conduits
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F1/00—Tubular elements; Assemblies of tubular elements
- F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
- F28F1/40—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only inside the tubular element
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
- F28F13/18—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by applying coatings, e.g. radiation-absorbing, radiation-reflecting; by surface treatment, e.g. polishing
- F28F13/185—Heat-exchange surfaces provided with microstructures or with porous coatings
- F28F13/187—Heat-exchange surfaces provided with microstructures or with porous coatings especially adapted for evaporator surfaces or condenser surfaces, e.g. with nucleation sites
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/05—Compression system with heat exchange between particular parts of the system
- F25B2400/054—Compression system with heat exchange between particular parts of the system between the suction tube of the compressor and another part of the cycle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2500/00—Problems to be solved
- F25B2500/09—Improving heat transfers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D21/00—Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
- F28D2021/0019—Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for
- F28D2021/0068—Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for for refrigerant cycles
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Geometry (AREA)
- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
Abstract
A refrigeration cycle device (1) is provided with a refrigerant circuit (2) and a refrigerant. The refrigerant circuit (2) has a compressor (4), a condenser (5), an expansion valve (6), an evaporator (7), and an internal heat exchanger (8). The refrigerant is a hydrocarbon refrigerant. The internal heat exchanger (8) has an inner tube (8a) and an outer tube (8 b). The internal heat exchanger (8) is configured such that: the refrigerant flowing through the inner tube (8a) from the condenser (5) to the expansion valve (6) is heat-exchanged with the refrigerant flowing through the outer tube (8a) from the evaporator (7) to the compressor (4) in the outer tube (8 b). The refrigerant flowing through the outside of the inner tube (8a) in the outer tube (8b) is entirely gaseous.
Description
Technical Field
The present invention relates to a refrigeration cycle apparatus.
Background
Conventionally, R32 refrigerant and R410A refrigerant have been used as refrigerants for refrigeration cycle devices. A refrigeration cycle apparatus is known in which a R290 (propane) refrigerant having a Global Warming Potential (GWP) smaller than that of R32 refrigerant or R410A refrigerant is used in a refrigerant circuit in order to reduce the influence on Global Warming. In addition, a refrigeration cycle apparatus including an internal heat exchanger for improving cooling capacity is known.
For example, japanese patent application laid-open No. 2008-164245 (patent document 1) describes a refrigeration cycle apparatus including an internal heat exchanger in which propane is used as a refrigerant in a refrigerant circuit. The refrigeration cycle apparatus described in this publication includes a compressor, a condenser, a heat exchanger, and an evaporator. This heat exchanger corresponds to an internal heat exchanger. The internal heat exchanger has an inner tube and an outer tube into which the inner tube is inserted. Refrigerant delivered from the compressor through the condenser to the internal heat exchanger is delivered through an inner tube within the heat exchanger to the evaporator. The refrigerant delivered to the evaporator is returned to the compressor through the outer tube in the internal heat exchanger. In the internal heat exchanger, heat is exchanged between the refrigerant flowing through the inner tube and the refrigerant flowing through the outer tube.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open No. 2008-164245
Disclosure of Invention
Problems to be solved by the invention
The refrigeration cycle apparatus described in the above publication does not describe the following: the refrigerant flowing through the inner tube and the outer tube in the outer tube of the internal heat exchanger is entirely a gas refrigerant. When the refrigerant flowing through the inner tube and the outer tube in the outer tube of the internal heat exchanger contains a liquid refrigerant, it is difficult to increase the degree of superheat of the refrigerant at the inlet of the compressor, and therefore it is difficult to improve the Coefficient of Performance (COP), which is the ratio of the power consumption of the refrigeration cycle apparatus to the power. Further, when the refrigerant flowing through the inner tube and the outer tube in the outer tube of the internal heat exchanger contains a liquid refrigerant, it is difficult to reduce the amount of the refrigerant in the internal heat exchanger.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a refrigeration cycle apparatus capable of improving the coefficient of performance of the refrigeration cycle apparatus by using a refrigerant having a small global warming coefficient, and reducing the amount of refrigerant in an internal heat exchanger.
Means for solving the problems
A refrigeration cycle device of the present invention includes a refrigerant circuit and a refrigerant. The refrigerant circuit includes a compressor, a condenser, an expansion valve, an evaporator, and an internal heat exchanger. The refrigerant flows through the refrigerant circuit in the order of a compressor, a condenser, an internal heat exchanger, an expansion valve, an evaporator, and an internal heat exchanger. The refrigerant is a hydrocarbon refrigerant. The internal heat exchanger has an inner pipe connected to the condenser and the expansion valve, and an outer pipe into which the inner pipe is inserted and connected to the evaporator and the compressor. The internal heat exchanger is constituted by: the refrigerant flowing through the inner tube from the condenser to the expansion valve is heat-exchanged with the refrigerant flowing through the outer tube from the evaporator to the compressor. The refrigerant flowing through the inside and outside of the outer tube is entirely gas.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the refrigeration cycle apparatus of the present invention, the refrigerant is a hydrocarbon refrigerant, and the entire refrigerant flowing through the inside and outside of the outer tube of the internal heat exchanger is a gas. Therefore, a refrigerant having a small global warming coefficient can be used. In addition, the coefficient of performance of the refrigeration cycle apparatus can be improved. Further, the amount of refrigerant in the internal heat exchanger can be reduced.
Drawings
Fig. 1 is a configuration diagram showing a refrigeration cycle apparatus according to embodiment 1 of the present invention.
Fig. 2 is a perspective view schematically showing the structure of an internal heat exchanger of a refrigeration cycle apparatus according to embodiment 1 of the present invention.
Fig. 3 is a sectional view taken along the line III-III of fig. 2.
Fig. 4 is a graph showing a relationship between the suction SH and the theoretical COP of the R290 refrigerant and the R32 refrigerant.
Fig. 5 is a cross-sectional view schematically showing the flow state of the refrigerant in the internal heat exchanger of comparative example 1.
Fig. 6 is a cross-sectional view schematically showing the flow state of the refrigerant in the internal heat exchanger of comparative example 2.
Fig. 7 is a cross-sectional view schematically showing the flow state of the refrigerant in the internal heat exchanger of the refrigeration cycle apparatus according to embodiment 1 of the present invention.
Fig. 8 is a partial sectional view taken along line VIII-VIII of fig. 7.
Fig. 9 is a cross-sectional view schematically showing the flow state of the refrigerant in the internal heat exchanger of the refrigeration cycle apparatus according to embodiment 2 of the present invention.
Fig. 10 is a partial sectional view taken along line X-X of fig. 9.
Detailed Description
Embodiments of the present invention will be described below with reference to the drawings. In the following, the same or corresponding portions are denoted by the same reference numerals, and description thereof will not be repeated in principle.
A configuration of a refrigeration cycle apparatus 1 according to embodiment 1 of the present invention will be described with reference to fig. 1. Fig. 1 is a configuration diagram showing a refrigeration cycle apparatus according to embodiment 1 of the present invention. The refrigeration cycle apparatus according to embodiment 1 of the present invention is, for example, an air conditioner. As shown in fig. 1, a refrigeration cycle apparatus 1 according to embodiment 1 of the present invention includes a refrigerant circuit 2, a control device 3, a condenser fan 10, an evaporator fan 11, and a refrigerant.
The refrigerant circuit 2 includes a compressor 4, a condenser 5, an expansion valve 6, an evaporator 7, and an internal heat exchanger 8. The compressor 4, the condenser 5, the expansion valve 6, the evaporator 7, and the internal heat exchanger 8 are connected by a pipe 9. The refrigerant circuit 2 is thus constructed. The refrigerant circuit 2 is configured to be able to circulate a refrigerant. The refrigerant circuit 2 is configured to: a refrigeration cycle is performed in which the refrigerant circulates while changing phase in the order of the compressor 4, the condenser 5, the internal heat exchanger 8, the expansion valve 6, the evaporator 7, and the internal heat exchanger 8.
In the refrigerant circuit 2, the refrigerant flows in the order of the compressor 4, the condenser 5, the internal heat exchanger 8, the expansion valve 6, the evaporator 7, and the internal heat exchanger 8. The refrigerant has a coefficient of performance that increases as the degree of superheat (suction SH) drawn into the compressor 4 increases. The refrigerant is, for example, a hydrocarbon refrigerant (HC refrigerant). Specifically, the refrigerant is, for example, propane (R290), isobutane (R600a), pentane (R601), butane (R600), ethane (R170), or propylene (R1270).
The control device 3 is configured to control the refrigerant circuit 2. The control device 3 is configured to perform calculations, instructions, and the like and control various mechanisms, devices, and the like of the refrigeration cycle apparatus 1. The control device 3 is configured to: the compressor 4, the expansion valve 6, the condenser fan 10, the evaporator fan 11, and the like are electrically connected to control their operations.
The compressor 4 is configured to compress and discharge a gas refrigerant that is sucked in. The compressor 4 is configured to be variable in capacity. The compressor 4 is constituted by: the capacity is changed by changing the frequency based on an instruction from the control device 3 to adjust the rotation speed. The compressor 4 uses a refrigerator oil (lubricating oil). The refrigerating machine oil is, for example, a polyalkylene glycol (PAG) oil having an ether bond, a polyol ester (POE) oil having an ester bond, or the like.
The condenser 5 is configured to condense the refrigerant compressed by the compressor 4. The condenser 5 is connected to the compressor 4 and the internal heat exchanger 8. The condenser 5 has a heat transfer pipe through which a refrigerant flows. The condenser 5 is, for example, a fin-tube type heat exchanger having a plurality of fins and heat transfer tubes such as round tubes or flat tubes penetrating the plurality of fins.
The expansion valve 6 is configured to expand and reduce the pressure of the liquid refrigerant condensed by the condenser 5. The liquid refrigerant condensed by the condenser 5 is expanded and decompressed in the expansion valve 6, and the refrigerant is brought into a gas-liquid two-phase state at the outlet of the expansion valve 6. The expansion valve 6 is connected to the condenser 5 and the evaporator 7. The expansion valve 6 is, for example, an electric expansion valve capable of adjusting the flow rate of the refrigerant based on an instruction from the control device 3. The amount of refrigerant passing through the expansion valve 6 is adjusted by adjusting the opening degree of the expansion valve 6.
The evaporator 7 is configured to evaporate the refrigerant decompressed by the expansion valve 6. The evaporator 7 is connected to the expansion valve 6 and the internal heat exchanger 8. The evaporator 7 has a heat transfer pipe through which refrigerant flows. The evaporator 7 is a fin-tube type heat exchanger having a heat transfer tube such as a round tube or a flat tube penetrating a plurality of fins and a plurality of fins, for example.
The internal heat exchanger 8 is configured to: the refrigerant on the outlet side of the condenser 5 is heat-exchanged with the refrigerant on the outlet side of the evaporator 7. In the internal heat exchanger 8, heat is exchanged between the refrigerant condensed by the condenser 5 and the refrigerant evaporated by the evaporator 7.
The pipe 9 connects the compressor 4, the condenser 5, the expansion valve 6, the evaporator 7, and the internal heat exchanger 8. The pipe 9 constitutes a gas-side refrigerant passage and a liquid-side refrigerant passage. The pipe 9 includes a first pipe portion 9a, a second pipe portion 9b, a third pipe portion 9c, and a fourth pipe portion 9 d. The first piping portion 9a is connected to the condenser 5 and the internal heat exchanger 8. The second piping section 9b is connected to the internal heat exchanger 8 and the expansion valve 6. The third piping portion 9c is connected to the evaporator 7 and the internal heat exchanger 8. The fourth piping portion 9d is connected to the internal heat exchanger 8 and the compressor 4.
In cooling, the condenser fan 10 is provided in an outdoor unit not shown. The condenser fan 10 is configured to forcibly blow outdoor air to the condenser 5. The condenser fan 10 is attached to the condenser 5, and configured to supply air as a heat exchange fluid to the condenser 5. The condenser fan 10 is configured to: the amount of air flowing around the condenser 5 is adjusted by adjusting the rotation speed of the condenser fan 10 based on an instruction from the control device 3, thereby adjusting the amount of heat exchange between the air and the refrigerant.
The evaporator fan 11 is provided in an indoor unit not shown. The evaporator fan 11 is configured to forcibly blow the indoor air to the evaporator 7. The evaporator fan 11 is attached to the evaporator 7, and configured to supply air as a heat exchange fluid to the evaporator 7. The evaporator fan 11 is constituted by: the amount of air flowing around the evaporator 7 is adjusted by adjusting the rotation speed of the evaporator fan 11 based on an instruction from the control device 3, thereby adjusting the amount of heat exchange between the air and the refrigerant.
The structure of the internal heat exchanger 8 will be described in detail with reference to fig. 1 to 3.
As shown in fig. 2 and 3, the internal heat exchanger 8 is a double-tube heat exchanger. The internal heat exchanger 8 has an inner tube 8a and an outer tube 8 b. The inner tube 8a has a tube shape. The outer tube 8b has a tubular shape. An inner tube 8a is inserted into the outer tube 8 b. That is, the inner tube 8a is disposed inside the outer tube 8 b. A gap GP is provided between the outer peripheral surface of the inner tube 8a and the inner peripheral surface of the outer tube 8 b. The gap GP may have a uniform size over the entire circumference in the outer circumferential direction of the inner tube 8 a.
As shown in fig. 1 to 3, the inner pipe 8a is connected to the condenser 5 and the expansion valve 6. The inner pipe 8a is connected to the condenser 5 via a first pipe portion 9a, and is connected to the expansion valve 6 via a second pipe portion 9 b. The inner tube 8a is configured to allow the refrigerant on the high-pressure side to flow therethrough. The outer pipe 8b is connected to the evaporator 7 and the compressor 4. The outer pipe 8b is connected to the evaporator 7 via a third pipe portion 9c, and is connected to the compressor 4 via a fourth pipe portion 9 d. The outer tube 8b is configured to allow the refrigerant on the low-pressure side to flow.
The internal heat exchanger 8 is configured to: the refrigerant flowing through the inner tube 8a from the condenser 5 to the expansion valve 6 exchanges heat with the refrigerant flowing through the outer tube 8a from the evaporator 7 to the compressor 4 in the outer tube 8 b. The internal heat exchanger 8 is configured to: the refrigerant flowing through the inner tube 8a and the refrigerant flowing through the outer tube 8b outside the inner tube 8a exchange heat with each other via the wall surface of the inner tube 8 a. The internal heat exchanger 8 is configured to: the refrigerant flowing through the inner tube 8a exchanges heat with the refrigerant flowing through the gap GP via the wall surface of the inner tube 8 a.
In the internal heat exchanger 8, all of the refrigerant flowing through the outside of the inner tube 8a in the outer tube 8b is gas. The refrigerant flowing through the gap GP is entirely gas. The refrigerant flowing through the outer tube 8a and flowing through the outer tube 8b is entirely in a dry state.
Next, the operation of the refrigeration cycle apparatus 1 will be described with reference to fig. 1 to 3. During the refrigeration cycle operation, the gaseous refrigerant compressed by the compressor 4 is discharged from the compressor 4, and is sent to the condenser 5 through the pipe 9 serving as a gas-side refrigerant path. In the condenser 5, the refrigerant flowing through the heat transfer pipe is condensed by discharging heat to the air. Then, the refrigerant passes through the first pipe portion 9a as a liquid-side refrigerant path and is sent to the internal heat exchanger 8. The refrigerant sent to the internal heat exchanger 8 through the first piping portion 9a passes through the inner pipe 8a of the internal heat exchanger 8, and then is sent to the expansion valve 6 through the second piping portion 9 b.
In the expansion valve 6, the liquid refrigerant is decompressed to become a two-phase gas-liquid refrigerant. The refrigerant decompressed by the expansion valve 6 is sent to the evaporator 7 through a pipe 9 serving as a liquid-side refrigerant path. The refrigerant takes in heat from the air in the evaporator 7, evaporates, and then passes through the third piping portion 9c as a gas-side refrigerant path to be sent to the internal heat exchanger 8. The refrigerant sent to the internal heat exchanger 8 through the third piping portion 9c returns to the compressor 4 through the fourth piping portion 9d after passing through the outer tube 8b of the internal heat exchanger 8.
In the internal heat exchanger 8, heat exchange is performed between the refrigerant (high-pressure side refrigerant) flowing through the inner tube 8a on the outlet side of the condenser 5 and the refrigerant (low-pressure side refrigerant) flowing through the outer tube 8b on the outlet side of the evaporator 7. Since the dryness of the refrigerant at the outlet of the evaporator 7 can be reduced by the internal heat exchanger 8, the heat transfer performance of the evaporator 7 improves. This improves the coefficient of performance (COP) of the refrigeration cycle apparatus 1.
Next, the operational effects of the refrigeration cycle apparatus 1 according to embodiment 1 of the present invention will be described in comparison with comparative example 1 and comparative example 2.
Here, in the refrigeration cycle apparatus 1 according to embodiment 1 of the present invention, R290 refrigerant is used as an example of the refrigerant. Comparative example 1 differs from the refrigeration cycle apparatus 1 according to embodiment 1 of the present invention in that the refrigerant is R32. Further, the global warming coefficient (GWP) of the R32 refrigerant is larger than that of the R290 refrigerant. Further, comparative example 1 is different from the refrigeration cycle apparatus according to embodiment 1 of the present invention in the following points: in the internal heat exchanger 8, the refrigerant on the low-pressure side flows through the inner tube 8a, and the refrigerant on the high-pressure side flows through the outer tube 8 b. That is, in comparative example 1, in the internal heat exchanger 8, the inner tube 8a is connected to the evaporator 7 and the compressor 4, and the outer tube 8b is connected to the condenser 5 and the expansion valve 6.
Fig. 4 is a graph showing a relationship between a theoretical coefficient of performance (hereinafter referred to as "theoretical COP") and a suction superheat (suction SH) of the compressor 4 in the case where each of the R290 refrigerant and the R32 refrigerant is used as the refrigerant in the refrigerant circuit 2. The coefficient of performance (COP) is a ratio of power consumption to power of the refrigeration cycle apparatus 1.
Referring to fig. 4, the theoretical COP of the R32 refrigerant decreases as the suction superheat (suction SH) of the compressor 4 increases. In contrast, the theoretical COP of the R290 refrigerant increases as the suction Superheat (SH) of the compressor 4 increases. This is because the R290 refrigerant and the R32 refrigerant have different characteristics. That is, when the suction superheat (suction SH) of the compressor 4 is increased, the coefficient of performance of the R290 refrigerant is superior to that of the R32 refrigerant.
In the case of the R32 refrigerant, the coefficient of performance is improved when the degree of superheat (suction SH) sucked into the compressor 4 is zero (0) compared to when the degree of superheat (suction SH) sucked into the compressor 4 is greater than zero (0) due to the characteristics of the refrigerant. Therefore, in order to improve the coefficient of performance, the refrigerant on the low-pressure side is brought into a wet state in the internal heat exchanger 8 so that the degree of superheat (suction SH) of the suction of the compressor 4 is not more than zero (0).
Fig. 5 is a cross-sectional view showing a flow state of the refrigerant inside the internal heat exchanger 8 in comparative example 1. Referring to fig. 5, in the internal heat exchanger 8 of comparative example 1, the refrigerant R1 flowing through the inner tube 8a is a low-pressure side refrigerant, and the refrigerant R2 flowing through the outer tube 8b is a high-pressure side refrigerant. The refrigerant R1 flowing through the low-pressure side of the inner tube 8a is in a gas-liquid two-phase state. The refrigerant R1 flowing through the low-pressure side of the inner tube 8a is circulated. That is, of the refrigerant flowing through the low-pressure side of the inner tube 8a, the gas refrigerant Ra flows through the center of the inner tube 8a, and the liquid refrigerant Rb flows along the outer portion of the wall surface of the inner tube 8 a. The liquid refrigerant Rb contacts the wall surface of the inner tube 8a serving as a heat transfer surface, and therefore the heat transfer performance is improved. However, since the refrigerant of comparative example 1 is R32 refrigerant, the global warming coefficient is larger than that of R290 refrigerant. Therefore, in comparative example 1, the global warming coefficient of the refrigerant cannot be decreased.
Fig. 6 is a cross-sectional view showing the flow state of the refrigerant inside the internal heat exchanger 8 in comparative example 2. Referring to fig. 6, the internal heat exchanger 8 of comparative example 2 is different from the refrigeration cycle apparatus 1 according to embodiment 1 of the present invention in that: the refrigerant R1 flowing through the inner tube 8a is a refrigerant on the low pressure side, and the refrigerant R2 flowing through the outer tube 8b is a refrigerant on the high pressure side. The refrigerant of comparative example 2 was propane (R290).
In the case where the degree of superheat of the refrigerant at the outlet of the evaporator 7 is zero (SH ═ 0), the performance of the evaporator 7 becomes good in theory. On the other hand, the larger the suction superheat (suction SH) of the compressor 4 is, the better the coefficient of performance is, due to the characteristics of the propane (R290) refrigerant. Therefore, in order to set the degree of superheat of the refrigerant at the outlet of the evaporator 7 to zero (SH ═ 0) and increase the degree of superheat of suction (suction SH) of the compressor 4, the degree of superheat of the refrigerant at the inlet on the low-pressure side of the internal heat exchanger 8 is preferably set to zero.
When the refrigeration cycle apparatus 1 is operated so that the coefficient of performance of the refrigeration cycle apparatus using propane (R290) as the refrigerant becomes good, the degree of superheat of the refrigerant at the outlet of the evaporator 7 becomes near zero. In this case, the degree of superheat at the outlet of the low-pressure side of the internal heat exchanger 8, i.e., at the inlet of the compressor 4, becomes zero or more. The refrigerant at the low-pressure inlet of the internal heat exchanger 8 is gaseous. In this case, since no liquid refrigerant is present in the refrigerant R1 flowing through the inner tube 8a of the internal heat exchanger 8, the refrigerating machine oil 20 is likely to be deposited on the inner surface of the wall surface of the inner tube 8 a. When the refrigerating machine oil 20 deposits on the wall surface of the inner tube 8a of the internal heat exchanger 8, the refrigerating machine oil 20 deposited on the wall surface of the inner tube 8a of the internal heat exchanger 8 becomes a thermal resistance, and therefore the heat transfer performance of the internal heat exchanger 8 is degraded.
Fig. 7 and 8 are cross-sectional views showing the flow state of the refrigerant in the internal heat exchanger 8 of the refrigeration cycle apparatus 1 according to embodiment 1 of the present invention. Referring to fig. 7 and 8, in the internal heat exchanger 8 of the refrigeration cycle apparatus 1 according to embodiment 1 of the present invention, the refrigerant R1 flowing through the inner tube 8a is a high-pressure side refrigerant, and the refrigerant R2 flowing through the outer tube 8b is a low-pressure side refrigerant.
In the interior of the inner heat exchanger 8, a heat transfer surface where the refrigerant R1 on the high pressure side flowing through the inner tube 8a and the refrigerant R2 on the low pressure side flowing through the outer tube 8b exchange heat becomes a wall surface of the inner tube 8 a. In addition to the wall surface of the inner tube 8a, which is a heat transfer surface for heat exchange between the refrigerant flowing through the outer tube 8b on the low pressure side and the refrigerant flowing through the inner tube 8a on the high pressure side, there is also a wall surface of the outer tube 8b, which is a heat transfer surface for heat exchange between the refrigerant flowing through the outer tube 8b on the low pressure side and the air outside the outer tube 8 b. Therefore, in the refrigeration cycle device 1 according to embodiment 1 of the present invention, the area of the wall surface on which the refrigerator oil 20 is deposited is larger than that of comparative example 2. Therefore, the amount of refrigerating machine oil deposited on the wall surface of the inner tube 8a as the heat transfer surface decreases. Therefore, it is possible to suppress the heat transfer performance of the internal heat exchanger 8 from being lowered due to the refrigerating machine oil deposited on the wall surface of the inner tube 8a becoming thermal resistance.
That is, in the refrigeration cycle apparatus 1 according to embodiment 1 of the present invention, propane (R290) refrigerant is used, and the high-pressure side refrigerant flows through the inner tube 8a of the internal heat exchanger 8, and the low-pressure side refrigerant flows through the outer tube 8 b. Then, the refrigerant at the inlet of the low-pressure side of the internal heat exchanger 8 is in a dry state. That is, the degree of superheat of the refrigerant at the inlet on the low-pressure side of the internal heat exchanger 8 becomes zero. This suppresses a decrease in heat transfer performance due to the deposition of the refrigerating machine oil in the internal heat exchanger 8. Therefore, the refrigeration cycle apparatus 1 can be operated with a good coefficient of performance.
According to the refrigeration cycle apparatus 1 of embodiment 1 of the present invention, since the refrigerant is a hydrocarbon refrigerant (HC refrigerant), a refrigerant having a small Global Warming Potential (GWP) can be used. The refrigerant flowing through the outside of the inner tube 8a in the outer tube 8b of the internal heat exchanger 8 is entirely gas. Therefore, the degree of superheat of the refrigerant at the inlet of the compressor 4 can be increased as compared to the case where the refrigerant flowing through the outside of the inner tube 8a in the outer tube 8b of the inner heat exchanger 8 contains a liquid refrigerant. Therefore, the coefficient of performance (COP) of the refrigeration cycle apparatus 1 can be improved. Further, the degree of superheat of the refrigerant at the outlet of the outer tube 8b of the interior heat exchanger 8 can be increased as compared to the case where the refrigerant flowing through the inside of the inner tube 8a in the outer tube 8b of the interior heat exchanger 8 contains a liquid refrigerant. Therefore, the amount of refrigerant in the internal heat exchanger 8 can be reduced.
According to the refrigeration cycle apparatus 1 of embodiment 1 of the present invention, the refrigerant is an HC refrigerant. Therefore, the Global Warming Potential (GWP) of the refrigerant can be reduced.
According to the refrigeration cycle apparatus 1 of embodiment 1 of the present invention, the expansion valve 6 is an electric expansion valve capable of adjusting the flow rate of the refrigerant. Therefore, the flow rate of the refrigerant can be adjusted by the electric expansion valve.
Unless otherwise specified, the refrigeration cycle apparatus 1 according to embodiment 2 of the present invention has the same configuration, operation, and effects as those of the refrigeration cycle apparatus 1 according to embodiment 1 of the present invention described above.
Referring to fig. 9 and 10, the refrigeration cycle apparatus 1 according to embodiment 2 of the present invention differs from the refrigeration cycle apparatus 1 according to embodiment 1 of the present invention in the configuration of the outer tube 8b of the internal heat exchanger 8.
In the refrigeration cycle apparatus 1 according to embodiment 2 of the present invention, the groove 30 is provided on the inner surface of the outer tube 8b of the internal heat exchanger 8. The groove 30 may be provided over the entire circumference of the inner surface of the outer tube 8b of the inner heat exchanger 8. The grooves 30 may be formed in a zigzag shape. The inner tube 8a of the internal heat exchanger 8 may not be provided with the groove 30. That is, no groove is provided on the inner surface and the outer surface of the inner tube 8a of the internal heat exchanger 8.
Since the groove 30 is provided only in the outer tube 8b of the inner heat exchanger 8, the refrigerator oil 20 is easily precipitated in the groove 30, which is a portion that does not contribute to heat transfer between the refrigerant flowing through the inner tube 8a and the refrigerant flowing through the outer tube 8b in the inner heat exchanger 8. Thereby, as compared with embodiment 1, it is possible to suppress a decrease in heat transfer performance due to the refrigerating machine oil deposited on the wall surface of the inner pipe 8 a.
According to the refrigeration cycle apparatus 1 of the present embodiment, the groove 30 is provided on the inner surface of the outer tube 8b of the internal heat exchanger 8. Since the heat transfer area of the outer pipe 8b is increased by the groove 30, the refrigerating machine oil 20 is likely to be deposited in the groove 30. Therefore, the decrease in heat transfer performance due to the refrigerating machine oil deposited on the wall surface of the inner pipe 8a can be suppressed.
According to the refrigeration cycle apparatus 1 of the present embodiment, the grooves 30 are formed in a zigzag shape. Therefore, the refrigerating machine oil is likely to be precipitated on the serrated bottom portion.
The presently disclosed embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the present invention is defined not by the above description but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.
Description of reference numerals
1 refrigeration cycle device, 2 refrigerant circuit, 3 control device, 4 compressor, 5 condenser, 6 expansion valve, 7 evaporator, 8 internal heat exchanger, 8a internal pipe, 8b external pipe, 9 piping, 10 condenser fan, 11 evaporator fan, 20 refrigerator oil, 30 groove.
Claims (5)
1. A refrigeration cycle device, comprising:
a refrigerant circuit having a compressor, a condenser, an expansion valve, an evaporator, and an internal heat exchanger; and
a refrigerant that flows in the refrigerant circuit in the order of the compressor, the condenser, the internal heat exchanger, the expansion valve, the evaporator, the internal heat exchanger,
the refrigerant is a hydrocarbon refrigerant and,
the internal heat exchanger has an inner pipe connected to the condenser and the expansion valve, and an outer pipe into which the inner pipe is inserted and connected to the evaporator and the compressor,
the internal heat exchanger is configured to: heat-exchanging the refrigerant flowing through the inner tube from the condenser to the expansion valve with the refrigerant flowing through the outer tube in the outer tube from the evaporator to the compressor,
the refrigerant flowing through the inner tube in the outer tube is entirely gas.
2. The refrigeration cycle apparatus according to claim 1,
a groove is arranged on the inner surface of the outer tube.
3. The refrigeration cycle apparatus according to claim 2,
the grooves are formed in a zigzag shape.
4. The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein,
the refrigerant is an HC refrigerant.
5. The refrigeration cycle device according to any one of claims 1 to 4, wherein,
the expansion valve is an electric expansion valve capable of adjusting the flow rate of the refrigerant.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP2019/000356 WO2020144764A1 (en) | 2019-01-09 | 2019-01-09 | Refrigeration cycle device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113227672A true CN113227672A (en) | 2021-08-06 |
Family
ID=71521528
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201980079923.1A Pending CN113227672A (en) | 2019-01-09 | 2019-01-09 | Refrigeration cycle device |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP3910262A4 (en) |
| JP (1) | JP7460550B2 (en) |
| CN (1) | CN113227672A (en) |
| WO (1) | WO2020144764A1 (en) |
Cited By (1)
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| TWI839240B (en) | 2023-05-31 | 2024-04-11 | 台灣奧利安產業股份有限公司 | Fluid heat exchange system |
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| WO2023139758A1 (en) * | 2022-01-21 | 2023-07-27 | 三菱電機株式会社 | Air conditioner |
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Also Published As
| Publication number | Publication date |
|---|---|
| EP3910262A4 (en) | 2021-12-29 |
| JP7460550B2 (en) | 2024-04-02 |
| JPWO2020144764A1 (en) | 2021-09-30 |
| EP3910262A1 (en) | 2021-11-17 |
| WO2020144764A1 (en) | 2020-07-16 |
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